The parotid gland in rats fed ad libitum exhibits a diurnal cyclic pattern which is correlated
with food intake. This is characterized by a change in gland weight, and is accompanied
histologically by correspondling changes in acinar diameter and granule content. The gland
levels of three enzymes (amylase, deoxyribonuclease, and ribonuclease), comprising 55 per
cent of the secretory protein, were minimal at the end of the eating cycle. These then
progressively increased and the highest levels were observed just prior to eating. During the …